<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #fu{
            position: relative;
            margin: 100px auto;
            height: 500px;
            width: 100px;
        }
        #fu>div{
            position: absolute;
            border-style: solid;
            border-width: 200px 0 200px 346px;
        }
        #fu> div:after {
            position: absolute;
            content: "Triangle";
            color: #fff;
            left: -250px;
            text-align: center;
        }
        #fu> div:first-child {
            border-color: #ff0000 transparent #ff0000 rgba(50, 50, 50, 0.6);
        }
    </style>
</head>
<body>
<div id="fu">
    <div></div>
</div>
</body>
</html>